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At first the car started and drove but it wouldn’t go into park. I dropped the oil pan to see that the selector had popped out of the slide shaft. I loosened the valve body and refitted the selector into the slide shaft. All was fine until as the transmission got hotter the shifter would get stiffer until too much force was required to get it into or out of park. I also noticed the transmission was very hot and when the engine was turned off some atf would leak out of the breather on top of the transmission. So I changed the oil cooler thinking it was defective. Now still the same issue.

When cold the transmission operates normally. As it reaches operating temperature and the fans come on it becomes harder to move the shifter. The transmission itself feels very hot to the touch. My 996 doesn’t feel that hot.

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By oil cooler I assume you mean atf cooler? Did you replace the atf? If so, was the correct fluid used? Is the atf properly filled to the correct level? Any evidence of intermix in the atf? Durametric will read trans codes...anything there?

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By oil cooler I assume you mean atf cooler? Did you replace the atf? If so, was the correct fluid used? Is the atf properly filled to the correct level? Any evidence of intermix in the atf? Durametric will read trans codes...anything there?

Yes I am referring to the atf cooler.Yes I changed the atf to a compatible fluid, filled until it came out the fill hole. No evidence of atf mixing but there is evidence of engine oil mixing. I don’t have Durametric.

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Was engine running and atf filled per the procedure (heated up to particular temperature range)? As you probably already know, the engine oil intermix can be a sign of several other issues that could be pretty serious. Is there intermix in the coolant?

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Well, based on that you may be low on atf. Sorry I don’t recall the proper temperature range off the top of my head but I can let you know tomorrow. The several times I have changed atf, it didn’t require running until fans coming on before reaching temp. So you could be running way higher than necessary during filling. You might also consider the heater valve to make sure it is opening to let the coolant flow through the atf cooler.

I had a tiptronic with intermix issues that worked well at low temp but once warm it would not function. Definitely others here with more experience than me on these things.

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With engine running and in park (with temp still low), fill with atf. Once fluid trickles out, with brake pedal pressed, move selector gear to each position and hold for about 10 seconds. Add more atf until it trickles out again. Check temp of atf inside trans. I usually use a digital probe.

Temperature must be between 30 and 40C at final check and filler screw must be put back on before 45C. Otherwise too much atf will be expelled and it will be low.

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. . . . and obviously the car must be level during the trans fill process.

When you say you used a compatible fluid, which one? I had a bad experience when a indy service garage, experienced with Porsche, used the wrong fluid. I knew right away and did 3 fluid changes in several weeks myself, by the book. Pentosin fluid. It's amber in color, not red. The red Pentosin is for other brands of German cars.

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Had the same issue on a 2,5 boxster with tiptronic. The reason for the stiff shifter, was the manual selector valve. Shift was fine when the transmission was cold, but as it warmed up it would get stiffer and eventually lock up. The material it is made from, can expand when heated, and this can lock up the valve. This has been an issue on quite a few BMW cars using the same ZF gearbox series.

I bought a new valve from ZF, around 11USD. You can leave the valve body in during the swap, just lower it a couple of inches. I fitted some longer bolts to keep the valve body aligned when lowering it.

Could be worth a try - as the valve is very cheap. It will take som oil and a new gasket though..

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I did not get the part number, but called the local ZF dealer and they ordered the valve for me, based on the information I send them on the gearbox (Picture of the type plate on the side of the transmission).